Smoothly transition from cached to live data

[MarcelGarus]

Before starting to implement this, we should probably wait for the offline caching to actually happen.
Depends on #57
Depends on #58

Is your feature request related to a problem? Please describe.
When a new news article / homework assignment / file or folder / course is added, the transition between the cached data and the live data is jarring.

Describe the solution you'd like
We should animate the new item into view.

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.